Positive electrode material for single crystal sodium ion battery, method for producing the same, positive electrode for sodium ion battery, and sodium ion battery

Abstract

To provide a mono-crystalline cathode material for a sodium-ion battery, capable of improving cycle performance of the sodium-ion battery.SOLUTION: A mono-crystalline cathode material for a sodium-ion battery has a chemical composition formula of Na1+aNi1-x-y-zMnxFeyMzO2, where -0.40≤a≤0.25, 0.08≤x≤0.5, 0.05≤y≤0.5, and 0≤z<0.26 are satisfied, and the M is one or a combination of two or more selected from a group consisting of Ti, Zn, Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P or Cu elements.EFFECT: The mono-crystalline cathode material for a sodium-ion battery has a specific chemical composition, a mono crystal topography and good structural stability and integrity. Particle fragmentation cannot be produced in a cyclic process, and meanwhile, cyclic stability of the sodium-ion battery can be improved.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention belongs to the technical field of sodium-ion batteries, and specifically relates to a cathode material for a single-crystal sodium-ion battery, a manufacturing method thereof, and a battery.

Background Art

[0002] With the intensification of competition in lithium-ion batteries, in addition to supply and demand relationships and resource regulations, the price of lithium salts has soared, and sodium-ion batteries with cost advantages have gradually become the focus of research by major enterprises and universities. Sodium-ion batteries operate on the same principle as lithium-ion batteries. However, in comparison, since sodium ions have a larger ionic radius and a slower diffusion rate, sodium ions have some disadvantages in terms of energy density and cycle characteristics.

[0003] After extensive research in various fields over the past decade, sodium-ion batteries mainly form products in systems such as transition metal oxides, Prussian blue, and polyanion phosphates. Among them, transition metal oxides have a relatively high specific capacity and thus gain popularity. However, poor cycle performance and low energy density are important factors affecting the application of cathode materials for sodium-ion batteries.

[0004] The transition metal oxides currently on the market are mainly divided into two types: nickel manganese iron copper-based oxides containing copper elements and nickel iron manganese-based oxides. In either type, by changing the different blending ratios of nickel, iron, manganese, and copper elements, cathode materials for sodium-ion batteries with different performances can be obtained. Also, due to the different blending ratios of the elements, the stability of the material when in contact with the electrolyte also changes. On the other hand, the factors affecting the cycle life of the cathode material for sodium-ion batteries are: 1. the reconstruction of the surface crystal structure during cycling; 2. the destruction of agglomerated particles due to anisotropic volume expansion during cycling. According to research, the connection structure between particles inside the agglomerated particles leads to an increase in the local current density, thereby generating a very large stress, which is found to affect the cycle characteristics of the material. Also, there is a phenomenon of inconsistent charge states between different parts inside the particles, which affects the electrochemical performance of the electrode.

[0005] Also, when the amount of sodium deintercalation of the cathode material for sodium-ion batteries is relatively large, the structure becomes extremely fragile, the active metals and oxygen in the lattice are displaced, reaching a certain high temperature and high pressure, and the atomic rearrangement and reconstruction gradually intensify, resulting in a large change in the volume and substance phase of the crystal grains. On the other hand, when the cathode material is deintercalated with sodium, the oxidizing power becomes stronger, and chemical and electrochemical reactions with the electrolyte are extremely likely to occur, making the material prone to deoxidation, the transition metal dissolves, especially the electrolyte is oxidized under high voltage, and H + is generated, the acidity of the electrolyte is improved, thereby causing the surface film of the electrode material to be damaged by HF, further changing the components and structure of the interface, and seriously affecting the electrochemical performance and cycle performance of the material.

Summary of the Invention

Problems to be Solved by the Invention

[0006] The technical problem to be solved by the present invention is to provide a single-crystal cathode material for sodium-ion batteries that improves the cycle performance of sodium-ion batteries.

[0007] In view of the above technical problems, as a result of the inventors' intensive research, a cathode material for a single-crystal sodium-ion battery having a single-crystal topography is obtained. The material has a complete structure, good processing performance, no particle cracking during cycling, and effectively reduces the generation of new interfaces due to particle cracking. By stabilizing the crystal structure of the material and applying it to a sodium-ion battery, especially a power-type sodium-ion battery, the high-temperature high-voltage cycle performance of the battery, especially the high-temperature stability, can be effectively improved.

Means for Solving the Problems

[0008] The technical solution of the present invention is as follows. The present invention provides a cathode material for a single-crystal sodium-ion battery. The chemical composition formula of the cathode material for the single-crystal sodium-ion battery is Na 1+a Ni 1-x-y-z Mn x Fe y M z O2, where -0.40 ≦ a ≦ 0.25, 0.08 ≦ x ≦ 0.5, 0.05 ≦ y ≦ 0.5, 0 ≦ z < 0.26, The M is one or more selected from the elements Ti, Zn, Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P or Cu.

[0009] Preferably, -0.33 ≦ a ≦ 0, 0.10 ≦ x ≦ 0.5, 0.15 ≦ y ≦ 0.5.

[0010] Preferably, the M is one or more selected from Zn, Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P or Cu, preferably one or more of Zn, Al, B, Ti, Ca, Y, Mg, Nb, Zr or Cu, and preferably, -0.40 ≦ a ≦ 0.25, 0.08 ≦ x ≦ 0.5, 0.05 ≦ y ≦ 0.5, 0 ≦ z ≦ 0.16.

[0011] Preferably, the positive electrode material for the single-crystal sodium ion battery has a microscopic topography that is a single-crystal topography under a scanning electron microscope. Preferably, the shape of the single-crystal topography particles is one or more of spherical, pseudo-spherical, polygonal, or layered sheet.

[0012] Preferably, in the powder X-ray diffraction spectrum (XRD) of the positive electrode material for the single-crystal sodium ion battery, the full width at half maximum FWHM(110) of the (110) diffraction peak at a diffraction angle 2θ of around 64.9° is 0.06 to 0.35.

[0013] Preferably, the tap density of the positive electrode material for the single-crystal sodium ion battery under a pressure of 7000 to 9000 kg is 2.8 to 4.2 g / cm 3 is.

[0014] Preferably, the moisture mass content of the positive electrode material for the single-crystal sodium ion battery is less than 3000 ppm, preferably less than 2800 ppm, and more preferably less than 2500 ppm.

[0015] Preferably, the pH value of the positive electrode material for the single-crystal sodium ion battery is within 13.1, preferably within 13.0.

[0016] Preferably, the specific surface area of the positive electrode material for the single-crystal sodium ion battery is 0.35 to 1.2 m 2 / g.

[0017] Preferably, the particle size D V 50 of the positive electrode material for the single-crystal sodium ion battery is 2.0 to 16.0 μm, preferably 4.0 to 13.0 μm.

[0018] The present invention further provides a method for manufacturing the above-mentioned cathode material for a single-crystal sodium-ion battery, which includes mixing raw materials containing a sodium source compound, an iron source compound, and a manganese source compound, and adding a nickel source compound and / or an M source compound as required, sintering, and pulverizing to obtain a cathode material for a single-crystal topography sodium-ion battery.

[0019] Preferably, the sintering temperature is 860-990 °C, preferably 880-980 °C, and preferably, the constant temperature time is 6-40 hours.

[0020] Preferably, the pulverization pressure is 0.1-1 MPa.

[0021] Preferably, the sodium source compound is one or more selected from the group consisting of sodium carbonate, sodium formate, sodium hydroxide, sodium acetate, sodium chloride, and sodium fluoride.

[0022] Preferably, the manganese source compound is one or more selected from the group consisting of manganese dioxide, manganese trioxide, manganese oxide, manganese carbonate, manganese oxalate, manganese sulfate, manganese acetate, manganese chloride, and manganese nitrate.

[0023] Preferably, the nickel source compound is one or more selected from the group consisting of nickel carbonate, nickel oxalate, nickel sulfate, nickel acetate, nickel chloride, and nickel nitrate.

[0024] Preferably, the iron source compound is one or more selected from the group consisting of ferric oxide, ferrous oxalate, ferric sulfate, ferric acetate, ferrous sulfate, ferrous acetate, ferrous nitrate, and ferric nitrate.

[0025] Preferably, the M-source compound contains an oxide or salts containing the M element. Preferably, the M-source compound contains one or more of calcium oxide, calcium hydroxide, boron trioxide, boric acid, niobium pentoxide, aluminum oxide, aluminum nitrate, aluminum acetate, titanium oxide, metatitanic acid, magnesium oxide, magnesium acetate, copper oxide, yttrium trioxide, zirconium oxide, zirconium oxychloride, zirconium acetate, sodium fluoride, lithium fluoride, zinc oxide, and copper sulfate.

[0026] The present invention further provides a positive electrode material for a single crystal sodium ion battery manufactured by the above manufacturing method.

[0027] The present invention further provides a positive electrode for a sodium ion battery, wherein the active material is the above single crystal sodium ion positive electrode material.

[0028] The present invention further provides a sodium ion battery including the above positive electrode for a sodium ion battery. The present invention further provides the application of the above single crystal sodium ion battery positive electrode material, or the above sodium ion battery positive electrode, or the above sodium ion battery in solar power generation, wind power generation, smart grid, distributed power plant, household energy storage battery, low-end two-wheeler battery or low energy density power battery.

Advantages of the Invention

[0029] The beneficial effects of the present invention are as follows. The positive electrode material for a single crystal sodium ion battery of the present invention has a specific chemical composition and single crystal topography, so the positive electrode material for a sodium ion battery has good structural stability and does not cause significant structural changes due to frequent desorption of sodium ions during charge and discharge of the sodium ion battery. In addition, the material has a complete structure, good processing performance, the particles do not crack during cycling, effectively prevents direct contact between the material surface and the electrolyte, especially contact with HF in the electrolyte, prevents the occurrence of side reactions, and improves the cycle stability of the sodium ion battery.

Brief Description of the Drawings

[0030]

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Embodiments for Carrying Out the Invention

[0031] To make the objectives, technical solutions, and technical effects of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described. The following described embodiments are some of the embodiments of the present invention, not all of them. All other embodiments obtained on the premise that those skilled in the art do not perform creative labor in combination with the embodiments in the present invention belong to the protection scope of the present invention.

[0032] D of the present invention V 50 is the particle size corresponding to when the percentage of the volume cumulative particle size distribution number in the sample reaches 50%.

[0033] To improve the cycle performance of a sodium ion battery, the present invention manufactures the positive electrode material for a sodium ion battery as single crystal particles, improves the structural stability of the material, effectively suppresses the change in structure, strengthens the reversibility of the material, effectively avoids direct contact between the material and the electrolyte, especially HF in the electrolyte, thereby preventing the occurrence of side reactions, suppressing the crystal phase transition of the material, and thereby improving the cycle stability of the material.

[0034] In one specific embodiment of the present invention, the present invention provides a cathode material for a single-crystal sodium-ion battery, and the chemical composition formula of the cathode material for the single-crystal topography sodium-ion battery is Na 1+a Ni 1-x-y-z Mn x Fe y M z O2, where -0.40 ≤ a ≤ 0.25, 0.08 ≤ x ≤ 0.5, 0.05 ≤ y ≤ 0.5, 0 ≤ z < 0.26, wherein M is one or more selected from the group consisting of Ti, Zn, Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, or Cu elements.

[0035] In a preferred embodiment of the present invention, in the above chemical formula 1, -0.33 ≤ a ≤ 0, 0.1 ≤ x ≤ 0.5, 0.15 ≤ y ≤ 0.5.

[0036] In a preferred embodiment of the present invention, the above M is one or more selected from Zn, Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, or Cu, preferably one or more of Zn, Al, B, Ti, Ca, Y, Mg, Nb, Zr, or Cu, and preferably 0 ≤ z ≤ 0.16.

[0037] In the present invention, the above cathode material for a single-crystal sodium-ion battery has a microscopic topography that is a single-crystal topography under a scanning electron microscope, and the shape of the single-crystal topography particles is one or more of spherical, pseudo-spherical, polygonal, or layered sheet.

[0038] In the present invention, in the powder X-ray diffraction spectrum (XRD) of the above-mentioned single-crystal sodium ion battery cathode material, the full width at half maximum FWHM(110) of the (110) diffraction peak at a diffraction angle 2θ of around 64.9° (in the present invention, around a diffraction angle X° means that the diffraction angle is X°±1°, for example, around 64.9° means 64.9°±1°, that is, 63.9° to 65.9°) is 0.06 to 0.35.

[0039] In the present invention, the tap density of the above-mentioned single-crystal sodium ion battery cathode material under a pressure of 7000 to 9000 kg is 2.8 to 4.2 g / cm 3 in between.

[0040] In the present invention, the specific surface area of the above-mentioned single-crystal sodium ion battery cathode material is 0.35 to 1.2 m 2 / g.

[0041] In the present invention, the particle size D V 50 of the above-mentioned single-crystal sodium ion battery cathode material is 2.00 to 16.0 μm, preferably 4.0 to 13.0 μm.

[0042] The specific surface area (BET) of the single-crystal sodium ion battery cathode material of the present invention is within a reasonable range, the intermolecular force on the material surface is at a relatively balanced position, and it is difficult to self-aggregate even in an environment with relatively high humidity.

[0043] The present invention further provides a method for manufacturing the above-mentioned single-crystal sodium ion battery cathode material, which includes mixing raw materials including a sodium source compound, an iron source compound, and a manganese source compound, and adding a nickel source compound and / or an M source compound as necessary, sintering, and pulverizing to obtain a single-crystal sodium ion battery cathode material.

[0044] In the above manufacturing method, the sintering is carried out at a temperature of 860 to 990°C for 6 to 40 hours. Preferably, the sintering temperature is 880 to 980°C, and the atmosphere used for sintering is air, oxygen, or a mixed gas of air and oxygen. In the above manufacturing method, the pulverization pressure is 0.1 to 1 MPa.

[0045] In the above manufacturing method, the sodium source compound contains a salt and / or hydroxide containing sodium element, and includes, for example, one or more of sodium carbonate, sodium formate, sodium hydroxide, sodium acetate, sodium chloride, and sodium fluoride.

[0046] In the above manufacturing method, the manganese source compound contains an oxide, hydroxide, or salt containing manganese element, and includes, for example, one or more of manganese dioxide, manganese tritoxide, manganese oxide, manganese carbonate, manganese oxalate, manganese sulfate, manganese acetate, manganese chloride, and manganese nitrate.

[0047] In the above manufacturing method, the nickel source compound contains an oxide, hydroxide, or salt containing nickel element, and includes, for example, one or more of nickel carbonate, nickel oxalate, nickel sulfate, nickel acetate, nickel chloride, and nickel nitrate.

[0048] In the above manufacturing method, the iron source compound contains an oxide, hydroxide, or salt containing iron element, and includes, for example, one or more of ferric oxide, ferrous oxalate, ferric sulfate, ferric acetate, ferrous sulfate, ferrous acetate, ferrous nitrate, and ferric nitrate.

[0049] In the above manufacturing method, the M source compound contains an oxide and / or salts containing M element, and includes, for example, one or more of calcium oxide, calcium hydroxide, boron trioxide, boric acid, niobium pentoxide, aluminum oxide, aluminum nitrate, aluminum acetate, titanium oxide, metatitanic acid, magnesium oxide, magnesium acetate, copper oxide, yttrium trioxide, zirconium oxide, zirconium oxychloride, zirconium acetate, sodium fluoride, lithium fluoride, zinc oxide, and copper sulfate.

[0050] The present invention further provides a positive electrode for a sodium-ion battery, wherein the active material is the above-mentioned single-crystal sodium-ion battery positive electrode material.

[0051] The present invention further provides a sodium-ion battery including the above positive electrode for a sodium-ion battery.

[0052] The sodium-ion battery of the present invention further includes a negative electrode, an electrolyte containing a sodium salt, a separator, and an aluminum plastic film. Specifically, the positive electrode is made of a material including a positive electrode current collector, a positive electrode active material, a binder, a conductive assistant, etc. applied to the positive electrode current collector, and the positive electrode active material is the positive electrode material of the present invention. The negative electrode is made of a material including a metallic sodium sheet or a current collector, a negative electrode active material, a binder, a conductive assistant, etc. applied to the current collector, the separator is a PP / PE film generally used in the industry, which is used to separate the positive electrode and the negative electrode from each other, and the aluminum plastic film is an enclosure of the positive electrode, the negative electrode, the separator, and the electrolyte.

[0053] The binder in the present invention is mainly used to improve the binding characteristics between the positive electrode active material particles and between the positive electrode active material particles and the current collector. As the binder in the present invention, a commercially available ordinary binder used in the industry can be selected. Specifically, the binder may be selected from polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymer, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1,1-difluoroethylene, polyethylene, polypropylene, styrene butadiene rubber, acrylate esterified styrene butadiene rubber, epoxy resin, nylon, or a composition thereof.

[0054] The conductive aid in the present invention can be selected from the ordinary conductive aids commercially available and used in the industry. Specifically, the conductive aid may be selected from carbon-based materials (such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black or carbon fiber), metal-based materials (such as metal powder or metal fiber containing copper, nickel, aluminum, silver, etc.), conductive polymers (such as polyphenylene derivatives) or compositions thereof.

[0055] The present invention further provides an application of the above single-crystalline sodium ion battery cathode material, or the above sodium ion electrode, or the above sodium ion battery in solar power generation, wind power generation, smart grid, distributed power plant, household energy storage battery, low-end two-wheeler battery or low energy density power battery.

[0056] Hereinafter, the beneficial effects of the present invention will be further described by specific examples.

[0057] The raw materials or reagents used in the present invention are all purchased from the main manufacturers in the market. When the manufacturer is not specified or the concentration is not specified, they are all analytical raw materials or reagents that are usually available, and are not particularly limited as long as they can achieve the intended effect. The instruments and equipment used in this example are all purchased from the main manufacturers in the market and are not particularly limited as long as they can achieve the intended effect. When specific techniques or conditions are not specified in this example, they are carried out according to the techniques or conditions described in the literature of the technical field or according to the product instructions.

[0058] The raw materials and instruments used in the following examples and comparative examples are as shown in Table 1.

[0059]

Table 1

[0060]

Table 2

[0061] (Example 1) With an elemental molar ratio of Na:Mn:Ni:Fe:B = 0.92:0.34:0.30:0.35:0.01 and a total weight of 1.63 kg, the corresponding weights of sodium carbonate, manganese carbonate, nickel carbonate, ferric oxide and boric acid were weighed respectively, and then added to an ultra-high speed multifunctional mixer and mixed at a rotation speed of 3300 r / min for 20 min. The uniformly mixed material was put into a muffle furnace and kept at a constant temperature of 885 °C for 18 h in an air atmosphere, and then naturally cooled. It was pulverized using an airflow pulverizer at a pulverization pressure of 0.60 MPa to obtain a positive electrode material C1 for a single crystal sodium ion battery.

[0062] The above positive electrode material was characterized and analyzed according to the following method. 1) Component analysis ICP was used to perform component analysis of the above positive electrode material. (1) Sample pretreatment A sample of 0.2000 - 0.2100 (accuracy from 0.001 g) was weighed into a 100 mL quartz beaker, 10 mL of aqua regia (1:1) was added to the quartz beaker along the beaker wall, covered with a watch glass, heated at 180 °C for 30 min, the solution was transferred to a 50 mL volumetric flask in its entirety, made up to the mark with deionized water and shaken well. 1 mL of the solution was aspirated from the well-shaken 50 mL volumetric flask into a 100 mL volumetric flask, 5 mL (25%) of nitric acid was added to the volumetric flask, and it was made up to the mark with deionized water. (2) Component analysis test was carried out using the calibration curve method. According to the above method, the chemical formula of the positive electrode material C1 for a single crystal sodium ion battery was measured to be Na 0.92 Ni 0.30 Mn 0.34 Fe 0.35 B 0.01 O2.

[0063] 2) Specific surface area It was measured according to the national standard GB / T19587 - 2006 Determination of specific surface area of solids by gas adsorption BET method. Analytical instrument: Tristar II 3020 fully automatic specific surface area and pore size distribution measuring device, Test parameters: Adsorbate N2, 99.999%, coolant liquid nitrogen, P0 measured, volume measurement mode, adsorption pressure deviation 0.05 mmHg, equilibrium time 5 s, selection of relative pressure points P / P0: 0.05, 0.1, 0.15, 0.2, 0.25, 0.30, Sample pretreatment: Weigh the empty sample tube + plug mass record M1, weigh a sample amount of 3.8 - 4.2 g, add it to a 9.5 mm specific surface area sample tube with a 3 / 8 inch ball valve, set 200 °C using a FlowPrep 060 degassing station, purge with an inert gas and heat degas for 0.5 h, take out and cool to room temperature, weigh the mass record M2 of the sample tube + plug + sample, the sample mass M = M2 - M1, perform an on-machine test and record the BET value. The results are shown in Table 3.

[0064] 3) Particle size Measured according to the national standard GB / T 19077 - 2016 laser diffraction method for particle size distribution, and the results are shown in Table 3. Test instrument: Malvern, Master Size 2000 laser particle size analyzer. Test steps: Weigh 1 g of powder, add it to 60 ml of pure water, perform external ultrasonic treatment for 5 min, inject the sample into the sample injection device, conduct the test, and record the test data. Test conditions: The test principle is the Mie (light scattering) theory, the detection angle is 0 - 135°, the external ultrasonic intensity is 40 KHz, 180 w, the particle refractive index is 1.692, the particle absorption rate is 1, the sample test time is 6 s, the background test snap number is 6,000 times, and the light obscuration rate is 8 - 12%.

[0065] 4) pH value Measure using a PHSJ-3F pH meter made by Leici. The specific method is as follows: accurately weigh a 5 g ± 0.05 g sample and place it in a beaker. Add deionized water at a mass ratio of the material to water of 1:9 to prepare a 10% suspension. Put a magnetic stirrer into the beaker and place the beaker on the tray of the magnetic stirrer. Set the rotation speed of the magnetic stirrer to 880 r / min and stir for 5 min. Filter the mixed solution using qualitative filter paper and a funnel, then place it in a constant temperature water bath set at 25 °C and perform constant temperature filtration for 20 ± 5 min. Rinse the electrode with the sample solution. After rinsing is complete, insert the electrode and the temperature sensor into the sample solution. When the reading is stable and the temperature indicates 25 °C, record the pH value. The results are shown in Table 3.

[0066] 5) XRD Test For the XRD test of the sodium ion cathode material in the examples of the present invention, an X’Pert PRO MPD analyzer was used. Test principle: The Bragg equation reflects the relationship between the direction of the diffraction line and the crystal structure. For diffraction to occur, the Bragg equation: 2dsinθ = nλ (d: crystal plane spacing, θ: Bragg angle, λ: X-ray wavelength, n: reflection order) must be satisfied. When the sample is irradiated with X-rays, the scattered X-rays of each atom in the crystal interfere with each other, generating a strong X-ray diffraction line in a specific direction. When the X-rays irradiate the sample from different angles, diffraction occurs on different crystal planes, and the detector receives the number of diffracted photons reflected from the crystal plane, thereby obtaining a spectrum of the relationship between the angle and the intensity. Test conditions: The light pipe uses a Cu target material, the wavelength is 1.54060, a Be window, incident optical path: solar slit 0.04 rad, divergence slit 1 / 2°, aperture diaphragm 10 mm, anti-scattering slit 1°, diffraction optical path: anti-scattering slit 8.0 mm, solar slit 0.04 rad, large Ni filter, scanning range 10~90°, scanning step 0.013°, residence time for each step 30.6 s, voltage 40 kV, current 40 mA. Powder sample preparation: Use a clean sampling spoon to put the powder into the groove of the slide glass (if it is a large particle sample, it is necessary to polish the powder to <50μm). Place one side of the blade (>20mm) against the surface of the slide glass, lift the other side slightly (the included angle <10°), use the edge of the blade to flatten the surface of the powder sample, rotate the slide glass by 90°, flatten it again, repeat the scraping several times in both directions. There should be no texture on the surface of the sample. Remove the excess powder around the slide glass and put it into the powder X-ray diffractometer. Sample analysis: Open the sample file tested using the analysis software High-Score Plus. First, determine the background, select peak detection to confirm the peaks, perform repeated fitting, record the Williamson-Hall plot to calculate the grain size, select the corresponding phase to perform phase matching and unit cell refinement, and record the half-width of the (110) diffraction peak near the diffraction angle 2θ of 64.9°. The results are shown in Table 3.

[0067] 6) Moisture Measure with reference to GB / T 11133-2015 Karl Fischer coulometric titration method. Use an 899 Coulometer + 885Compact Oven SC coulometer for testing. Weigh 0.5 - 0.8g of the sample using a moisture bottle with an accuracy of 0.0001g. The gas flow rate is 50 - 60ml / min, the heating temperature is 170°C, the initial drift ≤10μg / min, the end drift is 20μg / min, and the extraction time is 400s. The test results are retained to one decimal place, and the results are shown in Table 3.

[0068] 7) Compressed powder density [1] Place the circular mold on the stage of the electronic pressure tester, slowly manually increase the pressure to 1000kg, and then set the displacement and deformation to zero. [2] Weigh the powder with (5.0000 ± 0.1000), put it into the circular mold, gently shake it flat, and then place the upper pad of the mold on the sample. Note that in order to prevent the sample from spilling, both pads should face the sample with the non-cutting surface. [3] After filling the sample, place the mold on the stage of the electronic pressure tester, edit the program, increase the pressure to 8000 kg at a speed of 5 mm / min, maintain a constant voltage for 30 s, and then reduce the pressure to zero. [4] When the sample is held at a constant voltage until 8000 ± 10 kg (about 15 - 25 s after the pressure increase until reaching 8000 kg), record the pressure of the sample and read the sample height, with an accuracy of 0.001 cm. [5] After the reading is completed, manually lower the stage of the electronic pressure tester and take out the sample with a sampler. [6] After taking out the sample, clean the inside of the sample mold with a clean paper soaked in alcohol, ensure that the inside of the mold is clean, and the experiment is completed. [7] Calculate according to the results of the following formula and show the results in Table 3.

Equation

[0069] Figure 1 is an SEM image of the cathode material for a single - crystal sodium - ion battery in Example 1. It can be seen from Figure 1 that the material is composed of single - crystal particles and is polygonal and layered sheet - like.

[0070] The cathode material for a single - crystal sodium - ion battery in Example 1, polyvinylidene fluoride (PVDF) as a binder, and conductive carbon black (S.P) were thoroughly mixed at a weight ratio of 90:5:5, stirred to form a uniform slurry, coated on an aluminum foil current collector, dried, cold - pressed to make tabs, and an SEM test was performed on the tabs. As shown in Figure 7, it can be seen from Figure 7 that the material is still composed of single - crystal particles and no cracks occur on the surface of the material particles.

[0071] (Example 2) With an elemental molar ratio of Na:Mn:Ni:Fe:Cu:Zn = 0.81:0.31:0.25:0.28:0.12:0.04 and a total weight of 1.49 kg, sodium carbonate, manganese carbonate, nickel carbonate, ferric oxide, copper oxide, and zinc oxide were weighed respectively, and then added to an ultra-high-speed multifunctional mixer and mixed at a rotational speed of 3500 r / min for 15 min. The uniformly mixed material was put into a muffle furnace and kept at a constant temperature of 890 °C for 16 h in an air atmosphere, and then naturally cooled. It was pulverized using an airflow pulverizer at a pulverization pressure of 0.59 MPa to obtain a cathode material C2 for single-crystal sodium-ion batteries.

[0072] According to the component analysis method in Example 1, the chemical formula of the cathode material C2 for single-crystal sodium-ion batteries was measured to be Na 0.81 Ni 0.25 Mn 0.31 Fe 0.28 Cu 0.12 Zn 0.04 O2.

[0073] The above cathode material was tested by adopting the method in Example 1, and the test results are shown in Table 3.

[0074] Figure 2 is an SEM diagram of the cathode material for single-crystal sodium-ion batteries in Example 2. It can be seen from Figure 2 that the material is single-crystal particles and is polygonal and layered sheet-like.

[0075] The cathode material for single-crystal sodium-ion batteries in Example 2, polyvinylidene fluoride (PVDF) as a binder, and conductive carbon black (S.P) were thoroughly mixed at a weight ratio of 90:5:5, stirred to form a uniform slurry, coated on an aluminum foil current collector, dried, and cold-pressed to produce tabs. An SEM test was performed on the tabs. As shown in Figure 8, it can be seen from Figure 8 that the material is still single-crystal particles and no cracks occur on the surface of the material particles.

[0076] (Example 3) With an elemental molar ratio of Na:Mn:Ni:Fe:Zn:Al = 0.81:0.32:0.20:0.33:0.145:0.005 and a total weight of 1.75 kg, sodium carbonate, manganese(III) oxide, nickel oxalate, ferrous oxalate, zinc oxide, and aluminum oxide were weighed respectively and added to an ultra-high-speed multifunctional mixer, then mixed at a rotational speed of 4000 r / min for 15 min. The uniformly mixed material was put into a muffle furnace and kept at a constant temperature of 960 °C for 10 h in an air atmosphere, then naturally cooled, and pulverized using an airflow pulverizer at a pulverization pressure of 0.62 MPa to obtain the positive electrode material C3 for single-crystal sodium-ion batteries.

[0077] According to the component analysis method in Example 1, the chemical formula of the positive electrode material C3 for single-crystal sodium-ion batteries was measured to be Na 0.81 Ni 0.2 Mn 0.32 Fe 0.33 Zn 0.145 Al 0.005 O2.

[0078] Adopt the method in Example 1 to test the above positive electrode material, and the test results are shown in Table 3.

[0079] Figure 3 is the SEM diagram of the positive electrode material for single-crystal sodium-ion batteries in Example 3. It can be seen from Figure 3 that the material is single-crystal particles and is polygonal and layered sheet-like.

[0080] The positive electrode material for single-crystal sodium-ion batteries in Example 3, polyvinylidene fluoride (PVDF) as the binder, and conductive carbon black (S.P) were thoroughly mixed at a weight ratio of 90:5:5, stirred to form a uniform slurry, coated on an aluminum foil current collector, dried and pressed to make tabs, and an SEM test was performed on the tabs. As shown in Figure 9, it can be seen from Figure 9 that the material is still single-crystal particles and no cracks occur on the surface of the material particles.

[0081] (Example 4) With an elemental molar ratio of Na:Mn:Ni:Fe:Ti:Y = 0.77:0.22:0.47:0.09:0.215:0.005 and a total weight of 2.21 kg, sodium carbonate, manganese carbonate, nickel carbonate, ferric oxide, titanium oxide, and yttrium oxide were weighed respectively, and then added to an ultra-high-speed multifunctional mixer and mixed at a rotation speed of 2800 r / min for 40 min. The uniformly mixed material was put into a muffle furnace and kept at a constant temperature of 940 °C for 11 h in an air atmosphere, and then naturally cooled. It was pulverized using an airflow pulverizer at a pulverization pressure of 0.65 MPa to obtain a positive electrode material C4 for single-crystal sodium-ion batteries.

[0082] According to the component analysis method in Example 1, the chemical formula of the positive electrode material C4 for single-crystal sodium-ion batteries is Na 0.77 Ni 0.47 Mn 0.22 Fe 0.09 Ti 0.215 Y 0.005 O2 as measured.

[0083] The above positive electrode material was tested by adopting the method in Example 1, and the test results are shown in Table 3.

[0084] Figure 4 is an SEM diagram of the positive electrode material for single-crystal sodium-ion batteries in Example 4. It can be seen from Figure 4 that the material is single-crystal particles and is polygonal and layered sheet-like.

[0085] The positive electrode material for single-crystal sodium-ion batteries in Example 4 was thoroughly mixed with polyvinylidene fluoride (PVDF) as a binder and conductive carbon black (S.P) at a weight ratio of 90:5:5, stirred to form a uniform slurry, coated on an aluminum foil current collector, dried and pressed to make tabs, and an SEM test was performed on the tabs. As shown in Figure 10, it can be seen from Figure 10 that the material is still single-crystal particles and no cracks occur on the surface of the material particles.

[0086] (Example 5) With an elemental molar ratio of Na:Mn:Cu:Fe:Zr = 0.85:0.43:0.2285:0.34:0.0015 and a total weight of 1.46 kg, the corresponding weights of sodium carbonate, manganese carbonate, copper oxide, ferric oxide and zirconium oxide were weighed respectively, and then added to an ultra-high speed multi-functional mixer and mixed at a rotational speed of 2500 r / min for 50 min. The uniformly mixed material was put into a muffle furnace and kept at a constant temperature of 890 °C for 14 hours in an air atmosphere, and then naturally cooled. It was pulverized using an airflow pulverizer at a pulverization pressure of 0.69 MPa to obtain a cathode material C5 for single crystal sodium ion batteries.

[0087] According to the component analysis method in Example 1, the chemical formula of the cathode material C5 for single crystal sodium ion batteries is Na 0.85 Mn 0.43 Cu 0.2285 Fe 0.34 Zr 0.0015 It was measured that O2.

[0088] The above cathode material was tested by adopting the method in Example 1, and the test results are shown in Table 3.

[0089] Figure 5 is an SEM diagram of the cathode material for single crystal sodium ion batteries in Example 5. It can be seen from Figure 5 that the material is single crystal particles and is polygonal and layered sheet.

[0090] The cathode material for single crystal sodium ion batteries in Example 5, polyvinylidene fluoride (PVDF) as a binder, and conductive carbon black (S.P) were sufficiently mixed at a weight ratio of 90:5:5, stirred to form a uniform slurry, coated on an aluminum foil current collector, dried and pressed to make tabs, and an SEM test was performed on the tabs. As shown in Figure 11, it can be seen from Figure 11 that the material is still single crystal particles and no cracks occur on the surface of the material particles.

[0091] (Example 6) With an elemental molar ratio of Na:Mn:Ni:Fe:Zn:Ca = 0.86:0.38:0.20:0.32:0.08:0.02 and a total weight of 1.76 kg, sodium carbonate, manganese carbonate, nickel carbonate, ferrous oxalate, zinc oxide, and calcium oxide were weighed respectively, and then added to an ultra-high-speed multifunctional mixer and mixed at a rotational speed of 3600 r / min for 35 min. The uniformly mixed material was placed in a muffle furnace and kept at a constant temperature of 935 °C for 20 h in an air atmosphere, and then naturally cooled. It was pulverized using an airflow pulverizer at a pulverization pressure of 0.66 MPa to obtain a cathode material C6 for single-crystal sodium-ion batteries.

[0092] According to the component analysis method in Example 1, the chemical formula of the cathode material C6 for single-crystal sodium-ion batteries was measured to be Na 0.86 Ni 0.29 Mn 0.38 Fe 0.32 Zn 0.08 Ca 0.02 O2.

[0093] The above cathode material was tested by adopting the method in Example 1, and the test results are shown in Table 3.

[0094] Figure 6 is an SEM diagram of the cathode material for single-crystal sodium-ion batteries in Example 6. It can be seen from Figure 6 that the material is single-crystal particles and is polygonal and lamellar.

[0095] The cathode material for single-crystal sodium-ion batteries in Example 6 was thoroughly mixed with polyvinylidene fluoride (PVDF) as a binder and conductive carbon black (S.P) at a weight ratio of 90:5:5, stirred to form a uniform slurry, coated on an aluminum foil current collector, dried and pressed to make tabs, and an SEM test was performed on the tabs. As shown in Figure 12, it can be seen from Figure 12 that the material is still single-crystal particles and no cracks occur on the surface of the material particles.

[0096] (Comparative Example 1) With a molar ratio of sodium to nickel manganese iron precursor of 0.83:1 and a total weight of 1.40 kg, sodium carbonate and nickel manganese iron precursor (Ni 0.27 Mn0.38 Fe 0.35 (OH)2) were weighed respectively and added to an ultra-high-speed multifunctional mixer, and mixed at a rotation speed of 3600 r / min for 35 min. The uniformly mixed material was put into a muffle furnace and kept at a constant temperature of 890 °C for 16 h in an air atmosphere, then cooled naturally, ball-milled and sieved to obtain the finished product D1.

[0097] According to the component analysis method in Example 1, the chemical formula of the cathode material D1 for sodium-ion batteries is Na 0.83 Ni 0.27 Mn 0.38 Fe 0.35 O2 as measured.

[0098] The above cathode material was tested by adopting the method in Example 1, and the test results are shown in Table 3.

[0099] SEM test was carried out on the cathode material for sodium-ion batteries in Comparative Example 1. As shown in Figure 13, it can be seen from Figure 13 that the material is a secondary particle aggregate formed by the aggregation of a plurality of primary particles.

[0100] The cathode material for sodium-ion batteries in Comparative Example 1 and polyvinylidene fluoride (PVDF) as a binder and conductive carbon black (S.P) were sufficiently mixed at a weight ratio of 90:5:5, stirred to form a uniform slurry, coated on an aluminum foil current collector, dried and pressed to make tabs, and SEM test was carried out on the tabs. As shown in Figure 14, it can be seen from Figure 14 that most of the secondary particle aggregates of the material are crushed and fresh interfaces are exposed.

[0101]

Table 3

[0102] As can be seen from Table 3, in the powder X-ray diffraction spectra (XRD) of the positive electrode materials for single crystal sodium ion batteries manufactured in Examples 1 to 6, the full width at half maximum FWHM(110) of the (110) diffraction peak at a diffraction angle 2θ of around 64.9° is 0.152 to 0.274, the moisture mass content is 2400 ppm or less, the pH is less than 13.1 in all cases, the specific surface area is 0.45 to 0.93 m 2 / g, and the particle size D V 50 is 4.1 to 12.6 μm, and the tap density is 2.95 to 3.92 g / cm 3 . When a sodium ion positive electrode material is manufactured with the chemical composition of Comparative Example 1, the moisture mass content is 4320 ppm, which is much larger than 3000 ppm, the pH is 13.46, which is larger than 13.1, and the specific surface area is also much smaller than that of the examples of the present invention.

[0103] (Experimental Example 1) Manufacture and performance evaluation of sodium ion batteries.

[0104] A CR2430 button type battery is manufactured according to the following method. Positive electrode manufacture: The positive electrode materials for sodium ion batteries manufactured in Examples 1 to 6 and Comparative Example 1 of the present invention and polyvinylidene fluoride (PVDF) as a binder and conductive carbon black (S.P) are sufficiently mixed at a weight ratio of 7:2:1, stirred to form a uniform slurry, applied to an aluminum foil current collector, dried and pressed to form tabs, denoted as PE-C1, PE-C2, PE-C3, PE-C4, PE-C5, PE-C6 and PE-D1 respectively. Punch out the positive electrode tab after pressing, weigh it, bake it, and assemble the battery in a vacuum glove box. First, place the bottom of the button-type battery case, then place the foamed nickel (2.5 mm) and the negative electrode sodium metal sheet (manufacturer: Shenzhen Youyan Technology Co., Ltd.) on the bottom of the case. Inject 0.5 g of electrolyte in an environment with a relative humidity of less than 1.5%. The electrolyte adopts a mixed solvent with a mass ratio of ethylene carbonate (EC), diethyl carbonate (DEC), and dimethyl carbonate (DMC) of 1:1:1, and the electrolyte is a 1 mol / L sodium hexafluorophosphate solution. Place the separator and the positive electrode tab, then cover and seal the button-type battery case to obtain a button-type battery with the model number CR2430, which are denoted as BA-C1, BA-C2, BA-C3, BA-C4, BA-C5, BA-C6, and BA-D1 respectively.

[0105] Perform a performance test on the battery on a battery test system according to the following method, and the results are shown in Table 4. 1) Capacity test Attach the manufactured button-type battery to the test bench and start the test program. Setting steps: Set the test temperature to 25 °C, let it stand for 4 hours, charge at a constant current of 0.1C until 4.0V, pause, let it stand for 5 minutes, and then discharge at a constant current of 0.1C until 2.0V to obtain the capacity at the said current and voltage. 2) Cycle test Attach the battery that has undergone the above capacity test to the test bench, start the test program, and the setting steps are as follows: Set the test temperature to 45 °C, let it stand for 4 hours, charge at a constant current of 0.1C until 4.0V, then charge at a constant voltage of 4.0V for 2h, let it stand for 5 minutes, and then discharge at a constant current of 0.1C until the cut-off voltage of 2.0V, let it stand for 5 minutes, and repeat the steps starting from the previous constant current charging to perform the cycle test, and the capacity retention rate corresponding to the number of cycles can be obtained.

[0106]

Table 4

[0107] As can be seen from Table 4, the sodium-ion batteries manufactured by adopting the cathode materials for single-crystal sodium-ion batteries produced in Examples 1 to 6 have a capacity of 133.0 to 140 mAh / g at a current of 0.1C and a voltage of 4.2V (the cut-off voltage is 2.0V), and the capacity retention rate is 90.05 to 94.24% after 50 cycles under the conditions of 4.0V to 2.0V and 0.1C / 0.1C. The sodium-ion battery manufactured by adopting the sodium-ion battery cathode material produced in Comparative Example 1 has a capacity retention rate of only 77.64% after 50 cycles under the conditions of 4.0V to 2.0V and 0.1C / 0.1C. It can also be seen from Fig. 15 that the capacity retention rate of the sodium-ion battery manufactured by adopting the cathode materials for single-crystal sodium-ion batteries produced in Examples 1 to 6 is significantly better than that of Comparative Example 1 during the cycle test.

[0108] After 50 cycles of Battery BA-C1, the battery was disassembled, the positive electrode tab was taken out, and an SEM test was conducted. As shown in Fig. 16, it can be seen from Fig. 16 that even after cycling, the single-crystal particles have no cracks and remain complete particles.

[0109] The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any way. Modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0110] (Appendix) (Appendix 1) A cathode material for a single-crystal sodium-ion battery, The chemical composition formula of the cathode material for the single-crystal sodium-ion battery is Na 1+a Ni 1-x-y-z Mn x Fe y M z O2, where -0.40 ≤ a ≤ 0.25, 0.08 ≤ x ≤ 0.5, 0.05 ≤ y ≤ 0.5, and 0 ≤ z < 0.26, The M is one or more selected from the elements of Ti, Zn, Co, Mn, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, or Cu. A cathode material for a single crystal sodium ion battery, characterized by the following.

[0111] (Appendix 2) -0.33 ≤ a ≤ 0, 0.10 ≤ x ≤ 0.5, 0.15 ≤ y ≤ 0.5 The cathode material for a single crystal sodium ion battery according to Appendix 1, characterized by the following.

[0112] (Appendix 3) The M is one or more selected from Zn, Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P, or Cu. The cathode material for a single crystal sodium ion battery according to Appendix 1, characterized by the following.

[0113] (Appendix 4) The M is one or more selected from Zn, Al, B, Ti, Ca, Y, Mg, Nb, Zr, or Cu. The cathode material for a single crystal sodium ion battery according to Appendix 1, characterized by the following.

[0114] (Appendix 5) -0.40 ≤ a ≤ 0.25, 0.08 ≤ x ≤ 0.5, 0.05 ≤ y ≤ 0.5, 0 ≤ z ≤ 0.16 The cathode material for a single crystal sodium ion battery according to Appendix 1, characterized by the following.

[0115] (Appendix 6) Under a scanning electron microscope, the microscopic topography of the cathode material for the sodium ion battery is a single crystal topography, and the shape of the single crystal topography particles is one or more of spherical, pseudo-spherical, polygonal, or layered sheet. The cathode material for a single crystal sodium ion battery according to Appendix 1, characterized by the following.

[0116] (Appendix 7) In the powder X-ray diffraction spectrum (XRD) of the positive electrode material for the single-crystalline sodium ion battery, the full width at half maximum FWHM(110) of the (110) diffraction peak near the diffraction angle 2θ is 0.06 to 0.35. The positive electrode material for a single-crystalline sodium ion battery according to Supplementary Note 1, characterized in that

[0117] (Supplementary Note 8) The tap density of the positive electrode material for the single-crystalline sodium ion battery under a pressure of 7000 to 9000 kg is 2.8 to 4.2 g / cm 3 is The positive electrode material for a single-crystalline sodium ion battery according to any one of Supplementary Notes 1 to 7, characterized in that

[0118] (Supplementary Note 9) The moisture mass content of the positive electrode material for the single-crystalline sodium ion battery is less than 3000 ppm. The positive electrode material for a single-crystalline sodium ion battery according to any one of Supplementary Notes 1 to 7, characterized in that

[0119] (Supplementary Note 10) The pH value of the positive electrode material for the single-crystalline sodium ion battery is within 13.1. The positive electrode material for a single-crystalline sodium ion battery according to any one of Supplementary Notes 1 to 7, characterized in that

[0120] (Supplementary Note 11) The specific surface area of the positive electrode material for the single-crystalline sodium ion battery is 0.35 to 1.2 m 2 / g, and the particle size D V 50 of the positive electrode material for the single-crystalline sodium ion battery is 2.0 to 16.0 μm. The positive electrode material for a single-crystalline sodium ion battery according to any one of Supplementary Notes 1 to 7, characterized in that

[0121] (Supplementary Note 12) Mixing raw materials containing a sodium source compound, an iron source compound, and a manganese source compound, and adding a nickel source compound and / or an M source compound as needed, followed by sintering and pulverization to obtain a cathode material for a single-crystal sodium-ion battery, A method for manufacturing a cathode material for a single-crystal sodium-ion battery according to any one of Appendices 1 to 7, characterized by the above.

[0122] (Appendix 13) The sintering temperature is 860 to 990 °C, A manufacturing method according to Appendix 12, characterized by the above.

[0123] (Appendix 14) The pulverization pressure is 0.1 to 1 MPa, A manufacturing method according to Appendix 12, characterized by the above.

[0124] (Appendix 15) The sodium source compound contains a salt and / or hydroxide containing sodium element, And / or, the manganese source compound contains one or more of oxides, hydroxides or salts containing manganese element, And / or, the nickel source compound contains one or more of oxides, hydroxides or salts containing nickel element, And / or, the iron source compound contains one or more of oxides, hydroxides or salts containing iron element, And / or, the M source compound contains oxides and / or salts containing M element, A manufacturing method according to Appendix 12, characterized by the above.

[0125] (Appendix 16) Manufactured by the manufacturing method according to Appendix 12, A cathode material for a single-crystal sodium-ion battery, characterized by the above.

[0126] (Appendix 17) The active material is the cathode material for a single-crystal sodium-ion battery according to any one of Appendices 1 to 7 or Appendix 16, Positive electrode for sodium ion battery.

[0127] (Appendix 18) A sodium ion battery comprising the positive electrode for sodium ion battery described in Appendix 17, characterized in that.

Claims

1. A positive electrode material for a single-crystal sodium-ion battery, wherein The chemical composition formula of the positive electrode material for the single crystal sodium ion battery is Na, except when the value of 1 - x - y - z is 0 or negative. １＋ａ Ni １－ｘ－ｙ－ｚ Mn ｘ Fe ｙ M ｚ O ２ where -0.40 ≤ a ≤ 0.25, 0.08 ≤ x ≤ 0.5, 0.05 ≤ y ≤ 0.5, and 0 < z < 0.

26. the M is one or more selected from the elements Ti, Zn, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P or Cu; the tap density of the positive electrode material for the single-crystal sodium-ion battery under a pressure of 7000 to 9000 kg is 2.8 to 4.2 g / cm3 in an area of 3.14 cm2; a positive electrode material for a single-crystal sodium-ion battery, characterized by the above.

2. -0.33 ≤ a ≤ 0, 0.10 ≤ x ≤ 0.5, 0.15 ≤ y ≤ 0.5; a positive electrode material for a single-crystal sodium-ion battery according to Claim 1, characterized by the above.

3. the M is one or more selected from Zn, Ti, Co, Al, Zr, Y, Ca, Li, Rb, Cs, W, Ce, Mo, Ba, Mg, Ta, Nb, V, Sc, Sr, B, F, P or Cu; a positive electrode material for a single-crystal sodium-ion battery according to Claim 1, characterized by the above.

4. the M is one or more of Zn, Al, B, Ti, Ca, Y, Mg, Nb, Zr or Cu; a positive electrode material for a single-crystal sodium-ion battery according to Claim 1, characterized by the above.

5. -0.40 ≤ a ≤ 0.25, 0.08 ≤ x ≤ 0.5, 0.05 ≤ y ≤ 0.5, 0 < z ≤ 0.16; a positive electrode material for a single-crystal sodium-ion battery according to Claim 1, characterized by the above.

6. under a scanning electron microscope, the microscopic topography of the positive electrode material for the sodium-ion battery is a single-crystal topography, wherein the shape of the single-crystal topography particles is one or more of spherical, pseudo-spherical, polygonal or layered sheet; a positive electrode material for a single-crystal sodium-ion battery according to Claim 1, characterized by the above.

7. in the powder X-ray diffraction spectrum (XRD) of the positive electrode material for the single-crystal sodium-ion battery, the full width at half maximum FWHM(110) of the (110) diffraction peak near the diffraction angle 2θ of 64.9° is 0.06 to 0.35; a positive electrode material for a single-crystal sodium-ion battery according to Claim 1, characterized by the above.

8. the moisture mass content of the positive electrode material for the single-crystal sodium-ion battery is less than 3000 ppm; a positive electrode material for a single-crystal sodium-ion battery according to any one of Claims 1 to 7, characterized by the above.

9. The specific surface area of the positive electrode material for the single-crystal sodium ion battery is 0.35 to 1.2 m ２ / g, and the particle size D Ｖ 50 of the positive electrode material for the single-crystal sodium ion battery is 2.0 to 16.0 μm. The positive electrode material for a single-crystalline sodium-ion battery according to any one of claims 1 to 7, characterized in that...

10. A method for producing a positive electrode material for a single-crystalline sodium-ion battery, comprising the steps of mixing raw materials including a sodium source compound, an iron source compound, a manganese source compound, and an M source compound, adding a nickel source compound if necessary, sintering, and pulverizing to obtain the positive electrode material. The method for producing a positive electrode material for a single-crystalline sodium-ion battery according to any one of claims 1 to 7, characterized in that...

11. The sintering temperature is 860 to 990 °C. The production method according to claim 10, characterized in that...

12. The pulverization pressure is 0.1 to 1 MPa. The production method according to claim 10, characterized in that...

13. The sodium source compound includes a salt and / or hydroxide containing sodium element. And / or, the manganese source compound includes one or more of an oxide, hydroxide, or salt containing manganese element. And / or, the nickel source compound includes one or more of an oxide, hydroxide, or salt containing nickel element. And / or, the iron source compound includes one or more of an oxide, hydroxide, or salt containing iron element. And / or, the M source compound includes an oxide and / or salts containing M element. The production method according to claim 10, characterized in that...

14. The positive electrode for a sodium-ion battery, wherein the active material is the positive electrode material for a single-crystalline sodium-ion battery according to any one of claims 1 to 7. Positive electrode for a sodium-ion battery.

15. A sodium-ion battery, characterized by including the positive electrode for a sodium-ion battery according to claim 14. The sodium-ion battery, characterized in that...

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